This invention relates to a series of novel imidate insecticides distinguished by the general formula ##STR2## in which
R is an optionally substituted aryl moiety; R.sub.2 is an optionally substituted alkyl, cycloalkyl or alkenyl moiety, X is sulfur, amino or C.sub.1 -C.sub.4 monoalkylamino and R.sub.3 is (a) an optionally substituted 3-phenoxyphenalkyl, 3-phenoxypyridylalkyl or 3-(4-pyridyloxy)phenalkyl moiety; (b) pentafluorobenzyl; or (c) 2-methyl-3-phenylbenzyl.
More specifically, the compounds have the formula ##STR3## in which
R.sub.1 is 4-halo; 4-methyl; 3,4-disubstitution in which the substituents are independently halo, methyl, trifluoromethyl, trifluoromethylthio, trifluoromethoxy; or a 3,4-alkylenedioxy group having from 1 to 4 carbon atoms, optionally substituted by up to 2 halogens;
R.sub.2 is methyl; ethyl; n-propyl; C.sub.3 -C.sub.7 branched alkyl; C.sub.1 -C.sub.6 haloalkyl; or cyclopropyl, optionally substituted by up to 4 methyl groups or up to 2 halogens;
R.sub.3 is ##STR4## in which m is 0 or 1;
A and B are independently N or --CH, PA1 R.sub.4 is hydrogen or halo; PA1 R.sub.5 is hydrogen, mono- or di-halo, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkylthio, trifluoromethyl, cyano, or C.sub.1 -C.sub.4 alkylsulfonyl; and PA1 R.sub.6 is hydrogen or methyl; PA1 (i) if R.sub.1 is 4-chloro and R.sub.2 is dichloromethyl, then X is not sulfur and R.sub.3 is not pentafluorobenzyl; PA1 (ii) if R.sub.1 is 4-fluoro and R.sub.2 is cyclopropyl, then X is not amino or monoalkylamino; and PA1 (iii) R.sub.2 is not 1,3-dihalopropyl.
(b) pentafluorobenzyl; or
(c) 2-methyl,3-phenylbenzyl;
X is sulfur, amino or C.sub.1 -C.sub.4 monoalkylamino; provided that:
The compounds of this invention demonstrate activity in controlling various types of insects, primarily in controlling lepidoptera.
Another aspect of this invention is an insecticidal composition comprising an insecticidally effective amount of a compound of the invention formulated with an insecticidally suitable diluent or carrier.
Another aspect of this invention is a method for controlling insects by administration of insecticidally effective amounts of the compounds or compositions of this invention to the locus of the insect infestation.
The term "halo" includes chloro, bromo, iodo and fluoro. Of these, chloro is preferred. "Alkyl" refers to saturated acyclic hydrocarbyl groups (straight or branched chain) having the indicated number of carbon atoms. "Haloalkyl" refers to such groups substituted by one or more halogens, preferably chloro. "Alkylsulfonyl" refers to an alkyl group of the indicated number of carbon atoms, bonded to a sulfonyl (--SO.sub.2) group. Preferred groups in this invention include methyl, ethyl, isopropyl, chloromethyl, dichloromethyl and methylsulfonyl.
Alkylenedioxy moieties include methylenedioxy (--O--CH.sub.2 --O--), 1,2-ethylenedioxy (--O--C.sub.2 H.sub.4 --O--), monohalomethylenedioxy ##STR5## dihalomethylenedioxy ##STR6## 1,1-ethylenedioxy ##STR7## and isopropylenedioxy --(O--C(CH.sub.3).sub.2 --O--), wherein "Hal" represents a halogen atom.
Unsubstituted groups having the formula ##STR8## include 3-phenoxybenzyl, 3-phenoxy-(alpha-methyl)benzyl, 3-phenoxyphenethyl, 3-phenoxypyridylmethyl and 4-pyridyloxybenzyl. Substituents include, for R.sub.4 : 4- and 6-mono-halo, particularly monofluoro; for R.sub.5 : 2-, 3- or 4-halo; 2,4- 3,4- or 3,5-dihalo; 4-trifluoromethyl; 4-cyano; 4-methoxy; 4-methylthio; and 4-methylsulfonyl.
The term "amino" as used herein indicates the group --NH--.
Compounds of this invention may be prepared by reaction of an imidoyl chloride with a mercaptan, an alkali metal mercaptide, or an amine according to the reaction: ##STR9## in which R, R.sub.2, and R.sub.3 are as defined above, M is an alkali metal, preferably sodium or potassium, and R.sub.7 is hydrogen or C.sub.1 -C.sub.4 alkyl.
Reaction (a) or (b) is conducted in a temperature range of from about -40.degree. C. to about 80.degree. C., most preferably from about -10.degree. to about 20.degree. C., for a time which may range from about 10 minutes to about 20 hours. The reaction may be conducted in the presence of a solvent, for example, an aromatic hydrocarbon such as benzene, toluene, xylene or naphthalene, or an ether, such as diethyl ether, diisopropyl ether, diisoamyl ether, dibutyl ether, furan, 1,2-dimethoxyethane, or tetrahydrofuran (preferably tetrahydrofuran).
Alkali metal mercaptides R.sub.3 S-M may be produced by reaction of an appropriate mercaptan, such as 3-phenoxybenzyl mercaptan, with an alkali metal-containing base, for instance, an alkali metal hydride (e.g., potassium or preferably sodium hydride) in the presence of a solvent which may be an aromatic hydrocarbon such as benzene, toluene, xylene or naphthalene or an ether, such as diethyl ether, diisopropyl ether, diisoamyl ether, dibutyl ether, furan, 1,2-dimethyoxyethane or tetrahydrofuran. In general, this reaction is conducted at reflux temperature under an inert atmosphere for a time which may range up to about 2 hours.
The imidoyl chloride may be prepared from a starting amine having the formula RNH.sub.2 or amide having the formula ##STR10## depending on availability. The amines are either generally available or may be prepared by procedures known in the art, for example, those described in "Compendium of Organic Synthetic Methods", Harrison et al. (Wiley-Interscience, New York, 1971).
The amides, if not available, may be produced by reaction of the amine with an appropriate acid chloride having the formula ##STR11## The temperature of this reaction ranges from about -40.degree. C. to about +80.degree. C. Suitable solvents include hydrocarbon solvents such as toluene and chlorinated hydrocarbon solvents such as methylene chloride, chloroform, carbon tetrachloride, ethylene dichloride, tetrachloroethane and the like, preferably methylene chloride. This reaction is conducted in the presence of a base, preferably a tertiary amine. Suitable bases include triethylamine, quinoline, dimethylaniline, diethylaniline, and pyridine. Triethylamine is the preferred base. The resulting amide is recovered and purified by conventional means.
The imidoyl chloride may be prepared from the amide by reacting it with a chlorinating agent such as phosphorus pentachloride in an organic solvent such as that utilized in the amide production (preferably methylene chloride) or alternatively using phosphorus oxychloride as the solvent. The reaction is carried out under an inert atmosphere for a time which may range up to 10 hours, preferably from 1 to 4 hours, at a temperature of from about 0.degree. C. to about 80.degree. C.
Before the imidoyl chloride-containing product is passed to the final step, all substances, such as phosphorus oxychloride or hydrogen chloride, which can react with the mercaptan or mercaptide in the final step, should be removed. This can generally be accomplished by evaporation or distillation.
If a mercaptan is used in reaction (a), the process is carried out in the presence of a suitable base. The base utilized is a tertiary amine such as that employed for production of the amide from the amine and is preferably triethylamine. This reaction is conducted in the presence of a suitable solvent such as that utilized in the reaction of the alkali metal mercaptide with the imidoyl chloride, and is preferably tetrahydrofuran. The reaction between the mercaptan and the imidoyl chloride can be exothermic; consequently the addition of imidoyl chloride should be carefully controlled. This process carried out at room temperature under reflux for a time of between about 30 and about 60 minutes. The product may be recovered by conventional techniques.
Mercaptans of the formula R.sub.3 SH are described in German Appln. 2,944,849. 3-Phenoxybenzylamine is described in European Application 6155.
Compounds in which X is sulfur may also be prepared by alkylation of a thioamide according to the equation: ##STR12## in which R, R.sub.2 and R.sub.3 are as defined above and Hal stands for halogen, preferably chloro.
The thioamides, if not readily available, may be produced by reaction of the corresponding amine and Lawesson's Reagent. Reaction (c) is generally conducted at a temperature of from about -20.degree. to about 80.degree. C., for a time of from about 1 to about 20 hours, in the presence of a solvent, for instance an aromatic hydrocarbon such as benzene, toluene, xylene or naphthalene, or an ether such as diethyl, diisopropyl, diisoamyl or dibutyl ether, furan, 1,2-dimethoxyethane or tetrahydrofuran and an appropriate base such as an alkali metal hydride.